Edge-gating applications have been developed that use an injection manifold that is in fluid communication with either a radial array of mold gates and associated mold cavities or a linear array of mold gates and associated mold cavities. When providing a melt stream to a mold gate, a nozzle tip for delivering the melt stream to the mold gate must be centered in the gate orifice under operating conditions to ensure even cavity filling. When providing the melt stream to a radial array of mold gates in an edge-gated application, injection manifolds known in the art tend to be cylindrical or puck-shaped, which results in thermal expansion of the injection manifold under operating conditions being directed primarily radially outward from a center of the injection manifold toward each nozzle tip and associated mold gate such that alignment between the nozzle tip and mold gate is substantially constant under both hot and cold conditions. Accordingly, each nozzle tip may have an upstream end thereof held within a side surface of the cylindrical or puck-shaped injection manifold and a downstream end thereof held within a cavity plate or cavity insert that forms the mold gate without thermal expansion adversely affecting operation thereof.
When providing the melt stream to a linear array of mold gates in an edge-gated application, injection manifolds known in the art tend to be rectangular in shape with a row of nozzle tips secured within each of the opposing sides of the injection manifold that are aligned with a corresponding row of mold gates. In order to assure alignment between each nozzle tip and its respective mold gate under operating conditions, in the cold condition a pitch spacing between adjacent nozzle tips/melt outlets of a rectangular injection manifold is less than a spacing between their corresponding mold gates, which may be formed within a cavity plate or a respective cavity insert. However with thermal expansion of a rectangular injection manifold occurring in both lateral and longitudinal directions, each nozzle tip may experience a different amount of movement towards and/or transverse to its mold gate depending on the linear position of the nozzle tip along its respective side of the injection manifold. If such a linear injection manifold feeds only four mold cavities having a relatively close pitch spacing, that is two per side, the injection manifold will be relatively small and heat expansion will be minimal such that each nozzle tip may have an upstream end thereof held within a side surface of the rectangular injection manifold and a downstream end thereof held within a cavity plate or cavity insert that forms the mold gate without thermal expansion adversely affecting operation thereof. Conversely, if a linear injection manifold feeds a larger number of mold cavities having a relatively close pitch spacing or a smaller number of mold cavities having a relatively large pitch spacing, such as eight mold cavities with four per side, for example, there may be as much as 0.2 mm-0.3 mm misalignment between the outermost nozzle tips/melt outlets of the injection manifold, and the corresponding mold gates in a cold condition. During the thermal expansion of heated components that occurs during injection molding operations, a misalignment of this magnitude may cause severe stress on a nozzle tip that is being held, as is conventional, by both the injection manifold and cavity plate/cavity insert, and may in some instances cause a downstream end of the nozzle tip to contact a wall of the cavity plate/cavity insert that surrounds the mold gate, which may damage the nozzle tip and or result in a molded part of poor quality.
Embodiments disclosed herein are directed towards edge-gated injection molding applications for providing a melt stream to a linear array of mold gates and associated mold cavities that solve at least the aforementioned problem associated with current linear array edge-gating solutions. In addition, embodiments hereof are directed to simplifying nozzle tip replacement in edge-gating applications that does not require complete disassembly of the mold and/or to relatively easily taking out-of-service an individual edge-gated mold cavity.